Field of the Invention
The present invention relates generally to diagnostic assays for analytes in a fluid sample. In particular, the invention relates to devices, methods, and test kits for detecting an analyte in a bodily fluid.
Description of the Related Art
Detection of human chorionic gonadotropin (hCG) in urine samples is routinely used to determine a woman's pregnant/non-pregnant status. Traditional one-step pregnancy test devices detect hCG by utilizing a double antibody system in a lateral flow format resulting in a “sandwich” complex of hCG, a capture antibody and a labeled antibody, which is captured at a specific detection area on a test strip. A digital version of the pregnancy test device consists of an opto-electronic reader powered by an internal battery that measures the absorbance/reflectance of the label particles specifically captured at the detection area of the test strip and automatically subtracts any non-specific background color from an adjacent area of the test strip that is outside the detection area. The adjusted measurement of absorbance/reflectance of accumulated label particles at the detection area is then compared to a preset threshold value and further processed into a clearly read YES+/PREGNANT or NO−/NOT PREGNANT digital result on a liquid crystal display (LCD) screen.
Although electronic readers provide the added convenience of eliminating the end-user step of interpreting the results of the test, a step required in traditional lateral flow devices, there is room for improvements. For an electronic reader system that incorporates a lateral flow test strip, one of the many challenges in increasing the detection sensitivity is the unpredictability of uneven migration of resolubilized reagents and sample flow which can affect the electronic interpretation of the test result resulting in an inaccurate test result determination. Unlike the lateral flow pregnancy test where the consumer merely looks for the presence of a line irrespective of its color intensity and its uniformity, in a digital pregnancy test it is extremely important that the test line is uniform in color intensity. However, this is not always possible due to the reasons cited above. Therefore, improved devices, methods, and test kits for electronic analyte assaying digital detection are desirable.